Whilst disposals of Bitcoin in Portugal ARE tax free if you are a tax resident and you haven't transacted for one year (FIFO), this is only true if:
- You sell for actual fiat, eg on an exchange
- You provide all the TX data (using a tool such as Koinly) and REPORT it
If you ever stop being a tax resident in Portugal, unsold bitcoin is considered a "deemed disposal" and 28% of your BTC is due to the tax-man.
What's that you say? You pulled it out of the exchange and into a cold wallet? This info is shared, remember.. And the burden of proof (ie, where it went and how it went) is on you. Boating accidents aren't helpful, any more than setting fire to your fiat salary would be.
There are some workarounds (eg, gifting). If others have insights, do share.